Screw-attaching means for electrical devices.



No. 738,059. PATEN-TED' SEPT. 1, v19.03.

H. T. PAISTE.

SCREW ATTACHING MEANS ECR ELECTRICAL DEVICES.

APPLICATION FILED`JULY 20. 1901.

No MODEL.

rUNITED STATES Patented September 1, 1903.

PATENT OEEICE.

HENRY T. PAISTE, OF PHILADELPHIA, PENNSYLVANIA.

` SPECIFICATION forming part of Letters Patent No. 738,059, dated September 1, 1903.

Application filed July 20, 1901. Serial No. 69,047. (No model.) l

l delphia, Pennsylvania, have invented certain Improvements in Screw-Attaching Means for Electrical Devices, of which the following is a specification.

My invention relates to certain improvements in screw-attaching means for electrical devices.

The object of my invention isto provide a reliable and inexpensive device by means of which a screw passing through a hole in a non-compressible substance and entering a piece of material on the other side thereof shall be kept from rattling` loose or becoming unscrewed even although subjected to excessive vibration and which shall be particularly applicable to electrical devices, such as porcelain switches, cut-outs, dic.

This object I attain as hereinafter set forth, reference being had to the accompanying drawings, in which- Figure l is a sectional elevation of a piece Of porcelain, showing my improved device applied to a screw passing therethrough. Fig. 2 is a plan view of the under side of the same. Fig. 3 is a perspective view of one form of screw used in connection with my improved device. Fig. et shows a form of recess used in connection with my device to prevent the possibility of the solidiiied compound being jarred out 3 Fig. 5, Va plan view of a modified form of recess which may be used in connection with my invention; and Figs. 6 and 7 are sectional elevation and plan views, respectively, of a further modified form.

In using switches and cut-outs as well as switchboards of marble, slate, and otherv similar material it has been found that metallic bolts or screws used to hold the pieces of metal thereto will sooner or later become loose owing to the excessive vibration to which such articles are invariably subjected. Many devices have been employed to overcome this trouble, and particularly in the case of porcelain switches and cut-outs much time has been expended to overcome this difficulty. Lock-nuts or lock-washers have been employed in this connection; but besides being more or less bulky they were found to be unreliable. In some cases the end of the screw has been riveted over in an endeavor to retain it in place; but this operation almost invariably cracks the porcelain and is at best but a poor expedient, in view of the fact that it is almost impossible to ever remove the screw.

By my invention I have provided a method of holding a screw permanently in position after it has once been screwed up, while still rendering it possible to remove said screw with great ease should such' removal ever become necessary.

In the above drawings, A represents a portion of a porcelain block in which is a recess a. This recess is preferably rectangular in outline or of a form the periphery of which has points at unequal distances from its center, and from its bottom a hole of any desired section extends through the block. An ordinary machine-screw with its head squared, as shown in Fig. 3, passes through this hole and is screwed into a piece of metal C on the other side of the block. It will be noted that the recess a, while being square in section, is sufiiciently large to allow the head b, the periphery of which has points at unequal distances from its center, of the screw B to freely turn therein, thus rendering it possible to enter the screw in the piece C and turn it up so that it holds the same tightly to the block A. After the said screw B has been set up to what is considered a sufficient amount the recess a is filled in with any desired form of melted compound a', and it will be seen that this iiows completely around the square head of the screw, effectually preventing any possible rotation thereof. It will further be understood that the metallic piece C in devices of the kind towhich my invention is particularly applicable is non-rotatable, being always held by at least one other screw besides the screw B or kept stationary by being recessed into the porcelain, (be.

While it is well known that the insurance companies have long required that the insu- I IOO been found to be utterly inadequate to accom plish this purpose. This will be understood when it is noted that the repeated expansions and contractions of the screw due to temperature changes sooner or later allowed more or less play between the porcelain and the compound and permitted the screw to loosen its hold on a metal piece, suoli as C.

By my invention there is a solid body of compound between thel sides of the screwhead and the sides Yof the recess, and this has been found to effectually prevent any possible turning` of the'screw, even permitting it to be twisted off before allowing the head to rotate.

It will be noted that I do not confine myself to any particular form of either the screwhead or the recess, as these may be of any desired form other than that of a circle. For example, in Fig. 5 I have shown a screw of the form illustrated in Fig. 3 used in connection with an ellipticalY recessY and inv Figs. G and 7 the same screw in a cylindrical recess provided withdepressions in its bottom surface. The principle in these cases is the same as that governing` the operation of the form of device shown in Figs. 1 and 2.

Should there be any probability of the cement within the recess c becoming loose or broken for any reason, the said -recess may be made undercut, as shown in Fig. 4i, thus eilectually retaining the hardened compound in place. f

I claim as my invention l. The herein-described improvement in screw-attaching means for electricalde'vices consisting in the combination of a block of non-conductin g material, having in it a recess of a form the periphery of which has points at unequal distances from its center, a hole extending frein the bottom of this recess through the block, a screw passing through the hole and having a head rigid with the shank of the screw and of a form the periphery of which has points at unequal distances from its center contained in the recess, said recess being of a size to allow the screw to be turned freely, a body coniined by the screw to that facerof the block opposite to the one in which the recess is made, and a fusible insulating compound in the recess surrounding Vthe screw-head and insulating it while preventing its rotation, substantially as described.

2. The herein-described improvement in screw-attaching means for Velectrical devices consisting in the combination of a blocl of non-'conductin g material, having in it a recess of a form the periphery of which has points at unequal distances from its center, a hole extending from the bottom of this recess through theY block, a screw passing through the hole and having a head of aform the pe riphery of which has points at unequal distances from its center contained in the recess, said lrecess being undercut and of a size toallow the screw to be turned freely, a body confined by the screw Yto that Vface of the block opposite tofthe one in which the recess is made, and a fusible insulating compound in the recess surrounding the screw-head and insulating it while preventing its rotation, substantially as described.

InV testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses..

WILLIAM E. BRADLEY, Jos. H. KLEIN. 

